President Barack Obama and Republican challenger Mitt Romney are arguing over how to address US challenges overseas in nearly back-to-back addresses Tuesday (local time) at the Clinton Global Initiative's annual meeting.

Foreign policy has again taken the spotlight from economic issues in the tight presidential race as Obama also addresses world leaders at the UNGeneral Assembly on Tuesday. His UNvisit will be brief so he can get back to campaigning for the less than 10 percent of voters who say they have yet to make up their minds for the November election.

The Obama and Romney speeches at the annual gathering founded by former President Bill Clinton follow deadly anti-American protests in Muslim countries in the past two weeks over an amateur anti-Islam film made in the US

Romney was to outline plans to rework the US foreign aid system, tying development money to requirements that countries allow US investment and remove trade barriers.

Romney on Monday (local time)assailed Obama's leadership abroad, criticizing him for what Romney said was minimizing the death of the US ambassador to Libya, Chris Stevens, amid the protests over the film. The White House has deemed the deadly assault on the consulate in Benghazi a terrorist attack.

Romney also seized on a comment that Obama made in an interview with CBS' "60 Minutes" that aired Sunday (local time). Obama said recent violence in the Mideast was due to "bumps in the road" on the way to democracy.

"I can't imagine saying something like the assassination of ambassadors is a bump in the road, when you look at the entire context, the assassination, the Muslim Brotherhood president being elected in Egypt, 20,000 people killed in Syria, Iran close to becoming a nuclear nation, that these are far from being bumps in the road," Romney told ABC television.

White House press secretary Jay Carney called Romney's accusations "desperate and offensive" in the late stages of a close race that seems to be trending the president's way.

Romney, under pressure himself from fellow Republicans over the way his campaign is run, said he was shifting to a more energetic schedule of public events, trying to reverse recent erosion in polls of the battleground states likely to decide the election.

The US president is not chosen by popular vote but by state-by-state elections, making states that don't reliably vote Democrat or Republican important in a tight race.

Obama has gained ground on Romney in recent surveys when potential voters are asked to compare the candidates' ability to fix the economy. Sluggish growth and national unemployment of 8.1 percent make the economy by far the dominant issue in the race.

Obama also has a healthy lead over Romney when voters are asked which candidate is better equipped to handle foreign policy. The president has not shied away from mentioning his decision to order the secret mission by US forces that killed terrorism mastermind Osama bin Laden in his Pakistani hideout more than a year ago.

At the United Nations, Obama planned a sweeping defence of his policy of engagement overseas.

"Today, we must affirm that our future will be determined by people like Chris Stevens, and not by his killers," Obama says in an advance excerpt of his speech released early Tuesday by the White House.

Former president Clinton is used to having presidential candidates address his annual global forum. Both Obama and Republican challenger Sen. John McCain spoke there in 2008.

Clinton just a few weeks ago lit up the Democratic National Convention with a point-by-point rebuttal of Romney's attacks on Obama and defence of the president's economic record.